Sidewall exhaust vent issues with icing (relating to deck building)

Question Icon
Posted by: from Calgary
7/3/2012 at 11:10:51 PM


Our sidewall exhaust vent ices up a lot over the winter. We are wanting to expand on our deck this summer and it would end up being directly below the vent. This is an example of the kind of ice buildup we get in the winter. (The cap we have points downwards compared to the picture below.)

Check out the link:

Is there a different fitting that will prevent this? I have searched everywhere online but I don't think I've found one. It's hard to know since I'm not really sure exactly what I'm searching for and a lot of the sites that have had something seem to be from the US and don't really talk about our exact issue. My husband fears that putting the deck below the vent (it ends up being just below the siding, so it's somewhat of a ground level deck) will cause blockage. He wants to notch a hole in the deck directly below it so that the ice will flow down as it has. I just feel there is a better solution. We have little kids and I know they'll make all sorts of trouble with that hole being there.

Anyways, I'm hoping that there are a few solutions for this and we'll be able to find the best one for us. Our deck is going to be built in the next few weeks so hopefully we'll have a solution before then.

Thanks for your time and help,


User Icon
Kevin from Urban Improvements in Orono
Date/Time7/4/2012 at 12:09:29 AM

I'm curious what this vent is from?? Is it your furnace exhaust or hot water tank??

Perhaps they could put an elbow on it and run it downwards and then exhaust it somewhere else?? This way it would go straight down and look fairly clean and solve your icing issue?

User Icon
Date/Time7/4/2012 at 7:32:15 AM


This vent that is showing on your link is the exhaust for the furnace. You need to be careful with this pipe.

If you build the deck over it or if it's to close to the wood decking and it plugs up it will shut off the furnace.

Best idea is to have a heating company move the vent into an other area away from the deck. You could take a chance one a hole under the vent, but it maybe problematic if you get a lot of snow build up and plug the pipe with snow and ice, the furnace will stop working.

Sounds like trouble, moving it will be the best

User Icon
Date/Time7/4/2012 at 10:13:18 AM


To build up lots of snow in winter that looks like your slope for 636 furnace exhaust pipe in out side and that brings fuel burning moisture out side and build up ice.

Just for reminder we have to check the slope should be toward furnace and instead conduced water should come out and build up ice should go inside the furnace and furnace should have drain pipe coming out and should go to floor drain and other hand exhaust end should be 90 and then go up about 12 inch and then 45 degree also should be insulated throughout

Now look like we are putting deck over we can extend 636 both pipes and come under or through deck rim end plat then we will 90 on exhaust pipe .

then 12 inch up then 45 but before doing we have to check our venting coming out form furnace inside our mechanical room. Also exhaust and air vent both should be in same zone.

And if water heater exhaust vent is also coming under deck that should be come along.

If that little complicated best way to call your area heating inspection and they are very help full and come out will give us good suggestion reason each area requirement is different and they are very knowledgeable and they are there to help us..


User Icon
Date/Time7/5/2012 at 12:11:08 AM

The exhaust pipe should be 636 sloped backwards to the furnace which would cut down on the moisture on the outside. the other pipe fresh air has to be 8 inches away from the outlet of this vent. the fitting on the end looks wrong this should be full size of the pipe diameter. The 636 specs also call for a reducer fitting to speed up the flue gases.

Look at ipex 636 or call your Hvac service company for this solution. And by no means build a deck over this pipe, If done you are going to be calling for service many times.

User Icon
Desirae in Calgary
Date/Time7/5/2012 at 1:20:27 AM

Yes, it is the furnace exhaust vent. I think we'll have to get a guy to come and look at it and figure out a solution. It just doesn't seem like there is a frost free cover/cap solution for it.

Thanks for your help, it has sent me in the right direction.

Take care,


Search the TrustedPros directory and discover the best contractors in your area.

Find your home service pro
Great renovations start with a great contractor.

Since 2004, TrustedPros has been helping homeowners find the right contractor for their home improvements and repairs.

Post Your Project

Within hours you'll be comparing offers from top-rated professionals. It's free to post and you're under no obligation to hire.

Trustedpros Inc. does not warrant the accuracy, completeness, safety, legality or usefulness of any Content, or Whether Content is Current and up-to-date, and TrustedPros Inc. Shall have no liability whatsoever with respect to your use or reliance upon any content or for content being removed or otherwise ceasing to be available. Please refer to the terms and conditions of use of this websites for more details.

Get Free Estimates

Post your project and compare offers from top-rated pros.